Laser marking is a marking technique that uses lasers and other forms of radiant energy to bond an additive marking substance to a wide range of substrates. Laser marking forms permanent marks on metals, glass and ceramic parts and is used in many applications, ranging from aerospace to awards and engraving industries. Laser marking differs from the more widely known techniques of laser engraving and laser ablation in that laser marking is an additive process, adding material to the substrate to form the marking instead of removing material as in those techniques.
For metal substrates, parts can be permanently marked with high contrast, high resolution marks for logos, bar-coding, and identification and serialization purposes without damage to the substrate. With glass and ceramics, complex surfaces can be decorated or marked and the traditional firing process replaced by a laser and a marking composition with a permanent bond of the composition and surface being formed in seconds.
Although satisfactory in many regards, a need remains for marks that exhibit increased contrast and marks that are more readily visible. In addition, for marks subjected to surface wear, abrasion or exposure to environmental factors, it would also be beneficial to improve bonding between the mark and the underlying substrate to prevent or reduce the potential for wearing or removal of the mark. Furthermore, certain marking compositions when provided in liquid form, exhibit poor stability and thus tend to separate into multiple phases. Thus, frequent mixing and agitation of the composition is necessary and particularly prior to and during application. Accordingly, in view of these and other concerns, a need exists for improved marking compositions and methods using such materials.